Figure 5: Damaged axons can be rescued by delayed calpain inhibition.

(a) Maximum intensity projection montages from a control experiment (dimethyl sulfoxide, DMSO application) and an experiment with calpain inhibitor III application (b) from 1 to 2-h p.i. Under control conditions, many calcium-elevated (magenta) axons have fragmented, while they are protected by calpain inhibition. Note that insets in a have been adjusted to more clearly show dim axonal fragments. For colour look-up table cf. Fig. 2a. (c,d) Calpain inhibitor-treated axons swell, but do not fragment for up to 8 h after contusion, even though intra-axonal calcium levels remain elevated (e,f; DMSO: 164 axons, 4 mice, versus calpain inhibitor III: 270 axons, 5 mice). (g,h) Calpain inhibition also protects at-risk axons (that is, those that have elevated calcium at 100-min p.i.; population boxed in e,f). Scale bar in a,b, 20 μm.